The fact that he was able to continue to pitch until receiving an “anti-inflammatory (I read that as cortisone) injection” this week is not as encouraging as it may seem. Fortunately it meant that his pain was not severe, but it also implies that he exacerbated the problem — the obvious consequence of ignoring it while remaining active.

An injection will calm the acute inflammation and rest will allow it to do its job. The rehab is important though, and a two-week layoff isn’t likely to resolve the underlying causes of Marcum’s condition.

The word impingement tells you much of what you need to know — structures are being compressed or pinched. Pain occurs in the upper joint, especially when the arm is elevated and rotated inwardly. Overhead athletes are prime targets. A rotator cuff tendon and a bursa are impinged in the narrow space formed by the acromion (a portion of bone that appears like a hood over the shoulder), a prominence on the head of the humerus (the bone of the upper arm) and the ligament that connects the clavicle (collar bone) to the shoulder blade at the acromion.

Chronic impingement can lead to wear and tear of the rotator cuff tendons that pass through this (subacromial) space — not a great scenario. If rotator cuff tendons become inflamed, swelling will further compromise the joint space, creating more impingement. Degenerative rotator cuff tears can result in complete rupture and are often associated with biceps tendon rupture as well.

A loss of strength of the outward rotators also has an adverse impact on shoulder joint mechanics. Strong outward rotators stabilize and depress the humeral head, keeping it from gliding upward and narrowing the space that the tendons and bursa require. It becomes a vicious cycle.

Rehab for shoulder impingement always entails working to reduce inflammation while normalizing joint mobility and addressing muscle strength and flexibility. If the rear portion of the joint capsule is tight, restricting internal rotation mobility, joint mobilization proves helpful. The presence of instability of the shoulder, generally in the front (anterior) compartment, complicates matters and may require surgery. Likewise, surgical intervention may be necessary if bone spurs or a hooked shaped acromion contribute to impingement.

If Marcum is expected to return to the lineup shortly, his condition is likely of the uncomplicated variety.

However, as with all overuse injuries, too much too soon leads to increased vulnerability.

Take heed, Marcum.

Are you concerned about Marcum, Mets fans, or do you think he’ll be good to go for the start of the season? Sound off with your thoughts and comments below…